Objective: Although endovascular therapy is effective in acute ischemic stroke (AIS) patients with occlusion of the internal carotid artery or proximal middle cerebral artery (M1), the benefit are uncertain in those with the occlusion of distal middle cerebral artery (M2). To select the patient with potentially beneficial effects of endovascular therapy, we aimed to establish the threshold of NIHSS score as a predictive factor for favorable outcome in the patient with M2 occlusion treated with medical therapy alone.
Methods: Among 2180 AIS patients admitted to our stroke center between October 2011 and February 2015 (ClinicalTrials.gov Identifier: NCT02251665), 72 patients met the following criteria; 1) arrived within 6 hours from the onset, 2) isolated M2 occlusion on MRA, and 3) ASPECTS of ≥ 6 on DWI. Three patients who received endovascular therapy were excluded. We evaluated predictive factors for favorable outcome, defined as a modified Rankin Scale (mRS) <3 or equal to the premorbid mRS at 90 days after the onset.
Results: A total of 69 patients (26 women, 79.9±8.6 years old) was analyzed, and favorable outcome was achieved in 38 patients (55%). The favorable outcome group had a younger age (median 78 vs 82, p=0.03) and a lower baseline NIHSS score (9.5 vs 15, p=0.07) than the poor outcome group. Using receiver operating characteristic curves analysis, the optimal cutoff value of NIHSS score to predict favorable outcome was 9 (AUC 0.626). After adjusting for age, sex, onset to door time, and intravenous thrombolysis, NIHSS<9 was an independent predictor of favorable outcome (OR 3.95; 95% CI 1.04-18.22).
Conclusion: In AIS patient with M2 occlusion who treated with medical therapy, the baseline NIHSS score <9 was related to favorable outcome.